Multi-Frequency Microwave Imaging System Prototype for Medical Imaging

Abstract

A microwave imaging (MWI) system prototype to reconstruct three-dimensional (3D) complex dielectric images of various dielectric phantom models is provided. The imaging cavity of this system is filled with a newly compounded emulsion that provides a long-term stable and a controllable range of background-to-target dielectric contrasts. The system utilizes a tapered patch antenna array that enables multi-frequency operation. The the enhanced variational Born iterative method with bounding constraints (BC-VBIM) is applied as the inverse solver. Multiple experiments with various phantoms are conducted to evaluate the system's performance and imaging capabilities. Phantom models being used in this work for system evaluation include single, double, and multiple spherical targets filled with various water-isopropyl alcohol mixtures and submerged either directly in the background emulsion or within another water-alcohol mixture that is submerged in the emulsion.

What is claimed is: 
     
         1 . A dielectric imaging system:
 an imaging cavity for holding a sample to be imaged;   a coupling fluid disposed in the imaging cavity;   a plurality of antennas positioned in electrical communication with the coupling fluid, the plurality of antennas configured to have a plurality of resonant frequencies, the plurality of antennas including a first subset of antennas configured as receiver antennas and a second set of antennas configured as transmitter antennas;   a source of power for the plurality of antennas;   a data acquisition and data post-processing system; and   a dielectric reconstruction system.   
     
     
         2 . The dielectric imaging system of  claim 1 , wherein a 3D dielectric map is created from measured data at each resonance frequency. 
     
     
         3 . The dielectric imaging system of  claim 2 , wherein the 3D dielectric map is created from measured data at a plurality of resonance frequencies. 
     
     
         4 . The dielectric imaging system of  claim 1 , wherein the data acquisition and data post-processing system is configured to execute data calibration and correction procedures. 
     
     
         5 . The dielectric imaging system of  claim 4 , wherein the data acquisition and data post-processing system is configured to implement a calibration procedure and post-processing algorithm, to acquire coherent scattering parameters of each transmit-receive pairs. 
     
     
         6 . The dielectric imaging system of  claim 1 , wherein the plurality of antennas is a tapered patch antenna array. 
     
     
         7 . The dielectric imaging system of  claim 6 , wherein the plurality of antennas is a quad-band tapered patch antenna array. 
     
     
         8 . The dielectric imaging system of  claim 1 , wherein the data acquisition and data post-processing system is configured to provide processed data to the dielectric reconstruction system. 
     
     
         9 . The dielectric imaging system of  claim 1 , wherein for the dielectric reconstruction system is configured to execute an inverse algorithm for dielectric imaging. 
     
     
         10 . The dielectric imaging system of  claim 9 , wherein the inverse algorithm is an enhanced variational Born iterative method with bounding constraints (BC-VBIM). 
     
     
         11 . The dielectric imaging system of  claim 9 , wherein the inverse algorithm can utilize measured data at a plurality of resonance frequencies for 3D dielectric imaging. 
     
     
         12 . The dielectric imaging system of  claim 1  configured to operate at frequencies from 0.5 to 3 GHz. 
     
     
         13 . The dielectric imaging system of  claim 1 , wherein the data acquisition and data post-processing system includes vector network analyzers (VNA) that use coherent receivers to characterize the phase and magnitude of measured signals. 
     
     
         14 . The dielectric imaging system of  claim 1 , wherein the data acquisition and data post-processing system includes a plurality of switches configured to select receiver and transmit channels. 
     
     
         15 . The dielectric imaging system of  claim 1 , wherein the coupling fluid is an oil-based emulsion. 
     
     
         16 . The dielectric imaging system of  claim 15 , wherein the coupling fluid includes food-grade oil, acid fluid, and a protein-based mixture.